The present invention relates generally to power cable, and particularly to a power cable system designed in conjunction with submersible pumping systems that are used in extremely high temperature, wellbore environments.
Submersible pumping systems are used in a wide variety of environments. An exemplary application includes the use of an electric submersible pumping system disposed within a wellbore for pumping a production fluid, such as petroleum. The electric submersible pumping system includes, among other components, a submersible motor that powers a submersible pump. The submersible pumping system is deployed on a deployment system, such as coil tubing or production tubing, and power is provided to the submersible motor by a power cable disposed along or inside the deployment system.
Sometimes, it is desirable to utilize submersible pumping systems in high temperature applications. High temperature applications, for example, occur in wells subject to steam floods and low to no-flow conditions. Production fluid recovery in such areas can expose the submersible pumping system, including the power cable, to temperatures exceeding 600xc2x0 Fahrenheit and up to or over 1,0000xc2x0 Fahrenheit.
One problem with existing systems is the inability of power cables and power cable connections to withstand such high temperatures. Typically, a conventional power cable and the connector, i.e. pothead, utilized to couple the power cable to the electric motor is limited to a maximum temperature of approximately 450xc2x0 Fahrenheit. Temperatures exceeding this level lead to degradation of the cable and connector materials. The degradation often can lead to power cable failure.
Previous attempts to adapt submersible pumping systems to high temperature environments have focused on the use of new elastomers in both cable and connector design. To date, however, such attempts have not resulted in a system able to withstand high temperature applications, herein defined as applications in which the power cable and/or connector are exposed to temperatures exceeding 450xc2x0 Fahrenheit.
It would be advantageous to create a submersible pumping system for application in high temperature environments.
The present invention features a submersible pumping system that may be deployed in a wellbore to pump a fluid disposed in a subterranean formation. The system includes an electric submersible pumping system having a motor and a pump powered by the motor. Additionally, a deployment system is coupled to the electric submersible pumping system to deploy it within the wellbore. A power cable is disposed along the deployment system and connected to the motor to provide power thereto. The power cable includes at least three conductors that are individually protected by a mineral insulation layer and a metallic sheath layer.
According to another aspect of the present invention, a power cable is provided for use in a subterranean environment. The power cable includes a plurality of conductors and a layer of insulation disposed about each of the conductors. A metallic sheath also is disposed about each conductor, and an armor layer encloses the plurality of conductors collectively. Additionally, a metallic connector of the type adapted for connection to a submersible motor is connected to the plurality of conductors. Specifically, each metallic sheath is coupled to and sealed to the metallic connector via a metal-to-metal connection.
According to another aspect of the present invention, a submersible system is designed for use in a subterranean environment. The system includes a power cable and a submersible motor. The power cable has a plurality of conductors capable of carrying three-phase power. A layer of insulation is disposed about each of the conductors, and a metal sheath jackets each layer of insulation. An armor is disposed about the plurality of conductors. At an end of the armor, a connector forms a metal-to-metal seal with the metal sheath about each conductor. The connector is designed for engagement with the submersible motor.